The present invention relates to a mold for continuous casting particularly for round or billet type ingots, particularly of steel, and including a tubular mold enveloped by facilities for cooling with feed and discharge for the cooling medium as well as an intermediate cooling guidance tube which together with the mold tube proper establishes an annular gap for guiding the cooling fluid such as water along the mold.
Molds of the type to which the invention pertains are for example used in continuous casting of steel as well as non-ferrous metals wherein in case of rounds the ingot has a diameter between 100 and 500 mm while in the case of billets the format runs from about 70 by 70 mm up to 200 by 200 mm. Austrian pat. No. 238,388 suggests mold for casting of this type and suggests particularly for economical and engineering reasons to provide the tubular mold with smooth surfaces on the inside as well as on the outside. Coolant flow is established through a coolant guiding tube having a wall thickness of about 4 mm. The tubular guiding sheet envelops the mold and establishes an annular gap vis-a-vis the mold on the outside thereof and having a gap width of about 6 to 8 mm. The tubular mold itself has usually a wall thickness of about 12 mm.
Molds constructed in the aforementioned manner usually have use-life of approximately not more than 150 charges particularly in the case of casting of steel after which the mold tube is to be exchanged for the new one.
Aside from the foregoing the known molds for billet or round castings usually produce an ingot which quite frequently deviates at the exit of the mold from the theoretically assumed and cast contour and exhibits a romboidal contour in case of a billet rather than a square shaped (desired) cross section. In the case of round cross section usually there is no deviation of shape or contour of the casting but in certain cases cracks and fissures were observed in the material. In the case of round casting the tubular mold itself exhibited cracks after certain period of time. Seemingly these two phenomena are unrelated; nevertheless it is an aspect of the present invention, that the underlying discovery remedies both problems.